Any page need contain header in YAML format and its must be a first thing in the page file.
Here is a basic example:

title: My Page
description: My page description
My page body.

Between these triple-dashed lines, you can set predefined page header variables or even create custom ones of your own. These variables will then be available to you to access in site templates.

Predefined Page Header Variables

Here is a list of predefined page header variables with example values:

title: Welcome  
description: Some description here   
keywords: key, words
  name: Sergey Romanenko
  email: awilum@msn.com
  url: https://github.com/Awilum
date: 2015-10-18 16:00
tags: tag1, tag2
robots: noindex, nofollow  
template: default (allows you to use different templates in your theme)  

Custom Page Header Variables

You can create your own custom page headers using any valid YAML syntax.

  twitter: @getflextype